Belgian media are reporting that these are the alleged terror suspects at Zaventem airport.

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Terror attacks at an airport and metro station in Brussels on Tuesday left 31 dead and 250injured.

ISIS claims its fighters are behind theattacks.

Belgian media has released images from surveillance footage of the suspected attackers at Brussels’s Zaventem airport. Two are believed dead, having blown themselves up. A manhunt is under way for one suspect who prosecutors believe fled thescene.

The suicide attackers have been identified as brothers Khalid el-Bakraoui, 27, and Ibrahim el-Bakraoui, 30.

The third attacker has been identified as 24-year-old Najim Laachraoui. Police had been hunting him before the Brussels bombings; he is believed to be an accomplice in the Paris attacks. Some reports say Laachraoui has been arrested, but Belgian authorities have notconfirmed.

At least seven Americans were among those wounded in the attacks, including three Mormon missionaries and a U.S. serviceman.

ISIS claimed responsibility for the terror attacks on an airport and a metro station in Brussels on Tuesday. The terror group issued a statement, which spread across extremist outlets on social media, that spoke of "martyrs" who blew themselves up in both the airport and metro station. Here is the extremist group’s claim, via the New York Times:

Islamic State fighters carried out a series of bombings with explosive belts and devices on Tuesday, targeting an airport and a central metro station in the center of the Belgian capital Brussels, a country participating in the coalition against the IslamicState.

Islamic State fighters opened fire inside the Zaventem airport, before several of them detonated their explosive belts, as a martyrdom bomber detonated his explosive belt in the Maalbeek metrostation.

Belgian prosecutor Frédéric Van Leeuw told reporters that authorities have not yet verified those claims, adding they cannot yet say whether there is a link between the November 13 Paris attacks and the massacre inBrussels.

On Wednesday the two suicide bombers were identified by Belgian state media as brothers Khalid el-Bakraoui, 27, and Ibrahim el-Bakraoui, 30. Police have been searching for them since the March 15 raid on an apartment in Brussels, which led to the capture of Paris attacker Salah Abdeslam. The brothers were known to police, but their previous crimes were not related to terrorism. The Times reports:

Ibrahim el-Bakraoui was sentenced to nine years in prison in 2010 after shooting at police officers following an attempted robbery of a currency exchangeoffice.

In 2011, Khalid el-Bakraoui was sentenced to five years in prison for attempted carjackings; at the time of his arrest, he had been in possession of assaultrifles.

The third attacker, wearing the white jacket and hat, has been identified as 24-year-old Najim Laachraoui. Laachraoui had ties to Salah Abdeslam, the final Paris suspect arrested last week. Authorities had been actively searching for him after Abdeslam’s capture; evidence indicates he is a likely accomplice to the Paris attacks — possibly one of the bomb-makers. Prosecutors believe he also carried an explosive into the airport. Originally, they thought he might have panicked and fled, but now they believe he intended to escape and flee. This morning, reports circulated that he had been arrested, but Belgian prosecutors confirmed later he was still on the run.

The third attacker, wearing the white jacket and hat, has been identified as 24-year-old Najim Laachraoui. Laachraoui had ties to Salah Abdeslam, the final Paris suspect arrested last week. Authorities had been actively searching for him after Abdeslam’s capture; evidence indicates he is a likely accomplice to the Paris attacks — possibly one of the bomb-makers. Prosecutors believe he also carried an explosive into the airport. Originally, they thought he might have panicked and fled, but now they believe he intended to escape and flee. This morning, reports circulated that he had been arrested, but Belgian prosecutors confirmed later he was still on the run.

A picture taken on March 22, 2016 shows a Belgian police vehicle driving past passengers who are evacuating the Brussels Airport of Zaventem.Photo: JONAS ROOSENS

The Belgian news agency Belga reports that shots were fired and shouts in Arabic were heard shortly before the two airport explosions. At least one of the blasts occurred in the departure hall near the American Airlines check-in counter. All flights were quickly canceled or diverted, and the complex was evacuated. “Initially I thought it was the sound of a suitcase falling down,” Jordy van Overmeir, a traveler at Zaventem, told Sky News. “Then I came outside of the airport on the parking lot and there I saw people with head wounds, people crying, more blood on the road and glasseverywhere.”

Suicide bombers were responsible for those two airport explosions. Police also discovered a third bomb in the airport that had failed to go off, reports ABC News. Authorities safely dismantled that explosive on the scene, but reports on Tuesday evening of another suspicious package have kept police swarming the Zaventem airport, and it remains completely closedoff.

Photos and video posted to social media show smoke billowing from the terminal as people fled Tuesdaymorning:

At least eight Americans were hurt in the airport attacks. Three Mormon missionaries, all from Utah, were seriously injured in the Zaventem blast. A member of the U.S. military and four of his family members were also apparently wounded, but the injuries are said to be minor, reports NBCNews.

Maelbeek Metro StationBombing

A victim receives first aid by rescuers, on March 22, 2016, near Maalbeek metro station in Brussels.Photo: EMMANUEL DUNAND/AFP/Getty Images

The Maelbeek metro station, the site of the third explosion, is close to European Union headquarters. The subway blast went off in the second car of a five-car train, just before the train was about to pull out of the station during the busy morning rush-hour commute. The metro bomb may have been the most deadly, leaving 20 dead and about 106wounded.

The bombings come four days after Salah Abdeslam, who’s believed to be the only surviving suspect from the Paris terror attack, was captured in Brussels. Belgian police had been warned to be on alert for retaliatory attacks. “We know that stopping one cell can … push others into action. We are aware of it in this case,” Interior Minister Jan Jambon said onMonday.

Prime Minister Michel said "what we feared has happened," adding that police are concerned that the attacks aren’t over. Authorities shut down all public transport in the city and advised residents to stay indoors. Officials lifted the lockdown around 4 p.m. local time on Tuesday, and some train service within the city began to resume, but residents were warned to "viligant." Belgium is still under a "Level 4" terror threat, its highestlevel.

Facebook activated its “Safety Check” feature; Belgian officials encouraged Brussels residents to contact family and friends on social media or via text to avoid overwhelming the phonelines.

Belgian officials also evacuated all nonessential workers from two nuclear facilities, reports the Times, though they stressed there was no specific threat against the sites. “This was done, based on new information, and the events of today. Extra security measures were taken,” said an official with the agency that oversees theseplants.

Security has also been stepped up across Europe, and the border between France and Belgium has been closed. German officials have also stepped up controls on its border with Belgium. France and the U.K.have also raised their terrorism threat level to the highesttiers.

German police arrested three Kosovan men driving in a car with Belgian plates near its border with Austria, says Reuters. Authorities detained them over concerns that they may be plotting a separate attack; police did not think they had ties to the Brusselsplot.

Meanwhile, U.S. officials, including the NYPD, said they are also on high alert, but there is no known threat at thistime.

As a precaution @TSA is deploying add’l security to major US airports and at various rail and transit stations - Secretary Johnson #Brussels

NYPD commissioner Bill Bratton and Mayor Bill de Blasio addressed security concerns at a press conference Tuesday morning. The NYPD mobilized quickly in response to the Brussels attacks, according to Bratton, and the department doubled the number of transit cops on duty during the morning rush. Expect more cops on subways and at popular landmarks.

Bratton: "We at any given time are very engaged in staying aware of potential threats in terms of individuals." Ramped up activity.

“We in New York City stand ready to fight in every way,” de Blasio toldreporters.

De Blasio and Bratton reunited on Tuesday evening to reassure New Yorkers that there was no "specific or credible" threat against the city. The duo even rode the subway to Times Square to really hammer home thatpoint.

The Port Authority has ramped up security at the World Trade Center and its other locations. Governor Andrew Cuomo called for stepped-up security at major air and train hubs and bridges and tunnels. He added more state troopers to patrol these sites and deployed about 400 National Guardsmen to the NYC area.

While there’s no known credible threat to NYS at this time, we're stepping up security at high-profile locations: https://t.co/dwSkshWtFp

Parts of Denver International Airport were evacuated Tuesday afternoon after reports of a suspicious package near one of the terminals. Police and its bomb squad investigated and cleared the scene, and finding no real threat. Airports across the country had ramped up security in the wake of the attacks.

Mourning, Tributes to BrusselsVictims

Governor Cuomo also announced Tuesday afternoon that One World Trade Center will display the colors of the Belgian flag in honor of the Brusselsvictims.

People are now gathering for a vigil in Place de la Bourse in the central part of Brussels. Soon after the attacks, visitors came to the site and scrawled prayers and messages in sidewalk chalk. As darkness settled on the city, mourners lit candles and left flowers and ballons. “Je Suis Bruxelles / Ik Ben Brussel” read a large sign strung across the growing memorial: “I AmBrussels.”

Belgium will observe a three-day period of national mourning that started Tuesday. The Guardian reports the entire country will join in a moment of silence Wednesday at 12 p.m. local time to pay its respects to thevictims.

Political Leaders Respond

President Obama delivered a short statement on the tragedy from Havana Tuesdaymorning.

“This is yet another reminder that the world must unite: We must be together regardless of nationality or race or faith in fighting against the scourge of terorrism,” Obamasaid.

French president François Hollande, months removed from last fall’s devastating attacks in his own country, called the bombings in Brussels an attack on all ofEurope.

Donald Trump was among the first American political figures to publicly comment on the tragedy. The GOP front-runner decried the attacks, as well as the city they took place in. “I know Brussels and Brussels is a total mess, and I’m not talking about the attacks today,” Trump told NBC’s Today show, referring to immigration policies that had, in his view, made the city ungovernable. Shortly after, he echoed that sentiment onTwitter.

Do you all remember how beautiful and safe a place Brussels was. Not anymore, it is from a different world! U.S. must be vigilant and smart!

The Democratic presidential candidates also weighed in. Hillary Clinton appeared on the Today show, saying, “The threat posed by the modern incarnation of terrorism is one that we have to be vigilantagainst.”

These terrorists seek to undermine the democratic values that are the foundation of our way of life. They will never succeed. -H

Congressional leaders on both sides of the aisle offered support and solidary with European counterparts. “This is a terrorist attack in the heart of Europe,” GOP Speaker of the House Paul Ryan said earlier. “As our countries have always done, we must confront this threat together. We must defend democracy and defeatterror.”

We stand in solidarity with the people of #Brussels, and pray for the victims of this horrendous act of terror.